Rifles are powerful and accurate long-barrel guns with signifcant range and stopping power. Automatic fire is generally difficult to control and tends to be avoided. .50 BMG, .338 Lapua, and the other anti materiel rifles are used when personnel are of secondary concern. Large, fast projectiles make short work of lightly armoured vehicles, allowing a team of shooters to quickly disable the engine, the driver, and often to destroy or incapacitate crew-served weapons as well. Engagement distances with computer-aided ballistics software has crept out to 3.5km using GPS-guided projectiles.